Patent GB-1355872-A (GB)
Title: Phosphono substituted alkylcephalosporins
IPC: C07F9/38
Filed: 1971-04-19
Abstract: 1355872 Phosphoro-substituted alkyl cephalosporins PFIZER Inc 19 April 1971 [7 Dec 1970] 25319/71 Headings C2A C2C and C2P The invention comprises cephalosporins of the general Formula I and pharmaceutically acceptable cationic salts thereof in which R 1  is alkyl, hydrogen, phenyl or substituted phenyl wherein the substituent is alkyl, alkoxy, chlorine, bromine, fluorine or trifluoromethyl; R 2  is hydrogen or R 1  and R 2  taken together with the carbon atom to which they are attached are cycloalkyl or 3 to 7 carbon atoms; R 3  is hydrogen or acyloxy alkyl wherein the acyloxy moiety is alkanoyloxy, benzoyloxy or substituted benzoyloxy wherein the substituent is chlorine, bromine, fluorine, alkyl, alkoxy or trifluoromethyl; each of R 4  and R 5  are the same or different and are H, alkyl, substituted alkyl wherein the substituent is alkoxy or fluoro; phenyl or substituted phenyl, the substituent being chlorine, bromine, fluorine, alkoxy, alkyl or trifluoromethyl, R 6  is hydrogen, hydroxy, acetoxy or tertiary amino and n is 0 or an integer from 1 to 8. Compounds of Formula I may be prepared from 7-amino cephalosporanic acid and closely related acids by acylation in a reaction-inert solvent with a derivative of the appropriate phosphono-substituted acid reactant. Such derivatives include the acid chloride, bromide or anhydride, especially the mixed anhydride with other carboxylic acids such as ethoxy and isobutoxy carbonic acid, at a pH of between approximately 6 and 9 at a temperature of 0‹ C. to 50‹ C. The acylation may also be carried out in an aqueous reaction medium, e.g. an unstable emulsion of water and a water immiscible organic solvent over a pH range of 2 to 4 and a temperature range of 0-50‹ C. It can also be carried out in the pH range of 6-9 in aqueous solution of 0‹ C. to 50‹ C. The compounds of Formula I may also be prepared by reaction of 7-aminocephalosporanic acid or a related acid with the appropriate acid reactant in the presence of a condensing agent such as 1,3- dicyclohexylcarbodiimide or an alkylacetylene. Additionally acylating agents such as the appropriate acid azide or an active ester or the ester of the carboxy moiety of the acid reactant with, e.g. N-hydroxphthalimide, N-hydroxysuccinimide, a phenol or a thiophenol, may be used. Further the 7-aminocephalosporanic acid or related acid may first be converted to a mono- or disilyl derivative by reaction with a triethylsilylhalide or a trialkylsilylamine which is then acylated with an appropriate organic acid acylating agent and hydrolysed to remove the protecting group. The phosphonoalkanoic acid or phosphonocycloalkane carboxylic acid or derivative thereof can, when R 4  and/or R 5  is hydrogen, be used as the free acid or as an alkali metal or amine salt of the phosphoric acid group, depending upon the pH of the reaction mixture. The phosphono alkanoic acid reactants are prepared by the half-condensation of the appropriate alkylene bromide (or chloride), Br-(CH 2 ) n -Br, with the sodio derivative of an ester of the appropriate malonic acid R 1 CH- (COOR) 2  followed by saponification, decarbonylation, and reaction with a metal derivative of the appropriate phosphite. Diethyl aryl malonates are prepared by condensing diethyl carbonate with an equimolar proportion of the desired ethyl aryl acetate in the presence of an excess of sodium ethylate with continuous removal of by-product alcohol. Compounds where R 1  is 2-methoxyphenyl, 3-methoxyphenyl, 3- isopropylphenyl, 2-n-butylphenyl, 4-methoxyphenyl, 3-ethoxyphenyl, 2-trifluoromethylphenyl, 3-trifluoromethylphenyl, 4-trifluoromethylphenyl, 2-isopropylphenyl, 2-n-butoxyphenyl, 4-n-butoxyphenyl, 4-t-butylphenyl may be prepared and hydrolysed to the corresponding malonic acids. A number of substituted arylacetic acids are prepared by the Arndt and Eistert synthesis. In the preparation of 4-trifluoromethylphenylacetic acid, 4-trifluoromethylbenzoyl chloride is treated with diazomethane to give the diazo ketone. The diazoketone is treated with concentrated ammonium hydroxide and silver nitrate solutions to give the amide which is then hydrolysed to give the acid. Arylacetic acids of formula R 1 -CH 2 -COOH where R 1  is 2-trifluoromethylphenyl, 3-trifluoromethylphenyl, 4-t-butylphenyl, 4-isopropoxyphenyl, 2-n-butoxyphenyl, 3-ethoxyphenyl, 2-nbutylphenyl, 3-n-butylphenyl, 4-fluorophenyl have been prepared using the appropriate diethylaryl malonates and alkylene bromides and a number of substituted arylacetic acids were prepared of general Formula III. The sodio derivatives of the dialkylmalonates were reacted with the alkylene bromides to give products of Formula III. The 1-carboxy-1- carboxymethylcycloalkane where the cycloalkane is cyclopropane, cyclobutane, cyclopentane, cyclohexane and cycloheptane are converted to the corresponding 1-carbomethoxy- 1-carboxymethylcycloalkanes by reaction with methanol containing concentrated sulphuric acid to give the 1-carbomethoxy-1-carbomethoxy derivative. The dimethyl ester is then reacted with aqueous potassium hydroxide, followed by acidification to give the 1-carbomethoxy-1- carboxymethylcycloalkane. The 1-carbomethoxy-1-carboxymethylcycloalkane is reacted with alkaline silver nitrate, followed by reaction of the product with bromine in carbon tetrachloride to give the corresponding 1-carbomethoxy-1-bromomethylcycloalkane. Diethylmalonate is alkylated with 1-carbomethoxy-1- bromomethylcyclobutane by reaction with sodium ethoxide in ethanol. The diethyl-(1- carbomethoxy-cyclobutylmethyl) malonate is hydrolysed in the presence of base to give 1- carboxy-1-carboxyethylcyclobutane. The following cycloalkyl derivatives of Formula IV where m is 2, 3, 4, 5, and 6 and the corresponding values of n are 0, 1, 4 and 8, 0, 1, 3, 6 and 8, 0, 1, 3 and 4, 0, 1 and 5 and 0, 1, 3 and 6, are prepared by repetition of the above procedures. The phosphonocycloalkane carboxylic acids of formula HOOC-CR 1 R 2 - (CH 2 ) n -PO(OH) 2  are prepared by hydrolysis of an ester of the appropriate phosphono acid in the presence of concentrated hydrochloric or hydrobromic acid. If the ester contains an alkoxy group, hydrolysis is carried out in the presence of dilute acid. The monoesters of the phosphono acids are prepared by treatment of the diesters with dilute base, followed by ion exchange. Pharmaceutical compositions suitable for oral or parenteral administration may be prepared from a pharmaceutically acceptable carrier together with at least one of the compounds of Formula I.